Enhanced interfacial properties of carbon fiber/epoxy composites by coating carbon nanotubes onto carbon fiber surface by one-step dipping method

A type of carbon fiber/carbon nanotubes (CF/CNTs) multi-scale reinforcement was prepared by one-step dipping method, in which silane coupling agent (3-glycidyl ether oxy-propyl trimethoxy silane, KH560) was used as the bridge between CF and CNTs. Results showed that CNTs were uniformly coated onto CF surface, and the surface chemical activity, wettability and single fiber tensile strength of modified CFs were all improved significantly. More importantly, the interfacial shear strength (IFSS) of CF/CNTs reinforced epoxy composite, CF/CNTs composite, observed by SEM, showed good interface adhesion. It was also found that the silane coupling agent and CNTs would enhance the interfacial properties synergistically. Besides, the bridging effect of CNTs as the interfacial reinforcing mechanism for CF/CNTs multi-scale reinforcement composite was put forward. This special reinforcing mechanism may be as the guiding principle for CF surface modification and interfacial properties enhancement.